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Rutgers professor speaks on first coronavirus human challenge trial

Nir Eyal, Henry Rutgers professor of bioethics and director of the Rutgers Center for Population-Level Bioethics, said human challenge trials provide faster reliable answers for the duration and related effects of vaccine protection than more rounds of conventional vaccine trials. – Photo by Courtesy of Cheryl Thiemann

With plans set for the first human challenge trial of a potential coronavirus disease (COVID-19) vaccine, questions have been raised concerning the safety and value of such trials, according to an article from the journal, Nature. 

While challenge trials carry risks for volunteers, those risks can be dramatically suppressed and are ethically acceptable when weighed against the humanitarian value of said trials, said Nir Eyal, Henry Rutgers professor of bioethics and director of the Rutgers Center for Population-Level Bioethics.

The trial, in which young, healthy people will be exposed to COVID-19 to test different vaccines, is planned to begin in January 2021 in a London hospital upon final regulatory and ethical approval, according to the article. Eyal said it will start with a dose escalation study to set the viral dosage for participants, so the actual challenge study would start from mid- to late spring 2021.

“After the first SARS-CoV-2 vaccine proves effective, there would remain enormous global health value to testing others, which may prove even more efficacious, safer, easier to deliver, cheaper, monopoly-breakers or simply possible to manufacture and distribute to uncovered global populations without undermining manufacture of the first vaccine proven,” he said. “The question would then arise how to test the efficacy of these later vaccines.”

For assessing new vaccines and discerning the duration and related effects of vaccine protection, a challenge trial would provide faster reliable answers than more rounds of conventional trials, Eyal said.

An estimate by development economist Pedro Rosa Dias, global health leader Ara Darzi and Eyal himself found that if a challenge trial helps shorten the duration of the pandemic by one month, it will have averted the loss of at least 720,000 years of life and 40 million years in dire poverty worldwide.

“I wish the U.S. had the wisdom to pursue a challenge study earlier,” Eyal said. “Such an early study would have accelerated vaccine development even more than the U.K. study will do.”

The National Institutes of Health (NIH) has been reluctant to start challenge studies, but is making preparations for conducting them, Eyal said. The main reason they did not conduct challenge trials earlier is that a report said setup for a challenge study would take from one to two years, he said.

Another reason for the delay was ethical concerns about challenge studies in the absence of rescue therapies for COVID-19 virus infections, which Eyal said seem misguided, as challenge studies already minimize severe risks to volunteers.

All current plans for challenge trials suggest recruiting only consenting young adults, who are free from major risk factors for severe COVID-19 illness, he said. The risk of death for the young adult population has been estimated to be approximately one-tenth of the risk of death from kidney donation.

Similar to live kidney donation, Eyal said challenge trials must be performed with the informed consent of the participants, who prove their comprehension of all risks and uncertainties.

“Just as the consensual nature of kidney donation helps justify risks to kidney donors, so does the challenge volunteer’s autonomous consent to being put at risk, for the greater cause of ending the pandemic earlier,” he said.


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